Light-emitting device

ABSTRACT

A light-emitting device includes: a rectangular shape with a first side, a second side opposite to the first side, and a third side connecting the first side and the second side; a light-emitting stack, comprising a lower semiconductor layer, an upper semiconductor layer, and an active layer between the lower semiconductor layer and the upper semiconductor layer; a first electrode formed on the lower semiconductor layer, comprising a first electrode pad and a first extension electrode; a second electrode formed on the upper semiconductor layer, comprising a second electrode pad and a second extension electrode; and a first current blocking layer formed between the lower semiconductor layer and the first electrode pad, wherein the first current blocking layer comprises a top surface and side surfaces; wherein the first electrode pad covers the top surface and the side surfaces of the first current blocking layer and contacts the lower semiconductor layer.

REFERENCE TO RELATED APPLICATION

This application a continuation application of U.S. patent application Ser. No. 15/692,759, filed on Aug. 31, 2017, which is a continuation application of U.S. patent application Ser. No. 15/228,529, filed on Aug. 4, 2016, which is a continuation application of U.S. patent application Ser. No. 14/185,586, filed on Feb. 20, 2014, now U.S. Pat. No. 9,412,906, and the content of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The application relates to a light-emitting device, and more particularly, to a light-emitting device having two electrodes on the same side of a substrate thereof.

DESCRIPTION OF BACKGROUND ART

The lighting theory and structure of light-emitting diode (LED) is different from that of conventional lighting source. An LED has advantages as a low power loss, a long life-time, no need for warming time, and fast responsive time. Moreover, it is small, shockproof, and suitable for mass production. Therefore, LEDs are widely adopted in the market. For example, LEDs can be used in optical display apparatus, laser diodes, traffic lights, data storage devices, communication devices, illumination devices, medical devices, and so on.

A light-emitting device may include a substrate, a light-emitting stack including an n-type semiconductor layer, an active layer, and a p-type semiconductor layer. The light-emitting stack may have a roughened structure on the surface or the substrate thereof to enhance light extraction.

In addition, the light emitting device can be further connected to other components in order to form a light emitting apparatus. The light-emitting device may be mounted onto a submount with the side of the substrate, or a solder bump or a glue material may be formed between the submount and the light-emitting device, therefore a light-emitting apparatus is formed. Besides, the submount further comprises the circuit layout electrically connected to the electrode of the light-emitting device via an electrical conductive structure such as a metal wire.

SUMMARY OF THE APPLICATION

A light-emitting device includes: a rectangular shape with a first side, a second side opposite to the first side, and a third side connecting the first side and the second side; a first electrode pad formed adjacent to the third side; a second electrode pad formed adjacent to the second side; a first extension electrode, extending from the first electrode pad in a direction away from the third side and bended toward the second side; and a second extension electrode, including a first branch and a second branch respectively extended from the second electrode pad; wherein a distance between the first electrode pad and the third side is smaller than a distance between the second electrode pad and the third side; wherein an end portion of the first branch includes a first arc bending to the third side and a minimum distance between the first branch and the first side is smaller than a minimum distance between the second branch and the first side.

A light-emitting device includes: a light-emitting stack including a rectangular shape with a first side, a second side opposite to the first side, a third side connecting the first side and the second side, and a forth side opposite to the third side; a transparent conductive layer, formed on the light-emitting stack; a mesa formed in the light-emitting stack, adjacent to the third side; a first electrode formed on the mesa, including a first stripe and a bending portion, wherein the first electrode is elongated from the third side in a direction away from the third side and bends toward the second side, and the bending portion is between the first stripe and the third side; a second electrode formed on the light-emitting stack, including: a second electrode pad adjacent to the second side; a first branch and a second branch on the transparent conductive layer, respectively extending from the second electrode pad, wherein an end portion of the first branch bends to the third side and a minimum distance between the first branch and the first side is smaller than a minimum distance between the second branch and the first side.

A light-emitting device includes: a light-emitting stack including a first side, a second side opposite to the first side, and an upper surface between the first side and the second side; a first electrode pad formed on the upper surface; a second electrode pad formed on the upper surface, and the first electrode pad is closer to the first side than the second electrode pad; and a first extension electrode including a first section extended from the first electrode pad toward the second electrode pad, and a second section extended from the first electrode pad toward the first side.

A light-emitting device includes: a light-emitting stack including a first side, a second side opposite to the first side, and an upper surface between the first side and the second side; a first electrode pad formed on the upper surface; a second electrode pad formed on the upper surface, and the first electrode pad is closer to the first side than the second electrode pad; and a first extension electrode including a first section extended from the first electrode pad and parallel to the first side, and a second section connected to the first section and perpendicular to the first side.

A light-emitting device includes: a light-emitting stack including a first side, a second side opposite to the first side, a third side connecting the first side and the second side, and an upper surface between the first side and the second side; a first electrode pad formed on the upper surface; a second electrode pad formed on the upper surface, wherein the first electrode pad is closer to the first side than the second electrode pad; and a first extension electrode including a first section extended from the first electrode pad in a direction away from the third side, and a second section connecting to the first section and perpendicular to the first side; wherein a distance between the first electrode pad and the third side is smaller than a distance between the second electrode pad and the third side.

A light-emitting device includes: a rectangular shape with a first side, a second side opposite to the first side, and a third side connecting the first side and the second side; a light-emitting stack, comprising a lower semiconductor layer, an upper semiconductor layer, and an active layer between the lower semiconductor layer and the upper semiconductor layer; a first electrode formed on the lower semiconductor layer, comprising a first electrode pad and a first extension electrode; a second electrode formed on the upper semiconductor layer, comprising a second electrode pad and a second extension electrode; and a first current blocking layer formed between the lower semiconductor layer and the first electrode pad, wherein the first current blocking layer comprises a top surface and side surfaces; wherein the first electrode pad covers the top surface and the side surfaces of the first current blocking layer and contacts the lower semiconductor layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C illustrate a light-emitting device in accordance with a first embodiment of the present application;

FIGS. 2A to 2B illustrates a light-emitting device in accordance with a second embodiment of the present application; and

FIG. 3 illustrates a light-emitting device in accordance with a third embodiment of the present application.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIGS. 1A to 1C, a light-emitting device in accordance with a first embodiment of the present application is disclosed, wherein FIG. 1B is a cross-sectional view of FIG. 1A along line AA′, and FIG. 1C is a cross-sectional view of FIG. 1A along line BB′. The light-emitting device 100 comprises: a light-emitting stack 111 comprising a first side 111 a, a second side 111 b opposite to the first side 111 a, and an upper surface 100 a between the first side 111 a and the second side 111 b; a first electrode pad 110 formed on the upper surface 100 a; a second electrode pad 114 formed on the upper surface 100 a, and the first electrode pad 110 is closer to the first side 111 a than the second electrode pad 114; and a first extension electrode comprising a first section 110 b extended from the first electrode pad 110 toward the second electrode pad 114, and a second section 110 a extended from the first electrode pad 110 toward the first side 111 a. The light-emitting stack 111 further comprises a third side 111 c and a fourth side 111 d opposite to the third side 111 c, and the first side 111 a, the second side 111 b, the third side 111 c and the fourth side 111 d form a rectangle, and the first side 111 a and second side 111 b are the shorter sides, and the third side 111 c and the fourth side 111 d are the longer sides. The first electrode pad 110 and the second electrode pad 114 can be aligned to each other in accordance with a straight line (not shown) perpendicular to the first side 111 a and the second side 111 b, and the first section 110 b and the second section 110 a are in stripe form and formed along the straight line. The length of the first side 111 a (or second side 111 b) and the third side 111 c can be represented by X and Y, respectively. The length of the first section 110 b and second section 110 a can be represented by a and b, respectively. The optimized design of the light-emitting device 100 can be in accordance with a formula: (a/b)=C(Y/X)−L, wherein C can be a value between 1.5 and 2, and L can be a value between 1 and 1.05 for adjusting the ratio of a/b when X and Y are predetermined. The light-emitting stack 111 can comprise a lower semiconductor layer 104, an active layer 106 and an upper semiconductor layer 108. The lower semiconductor layer 104 can comprise n type, and the upper semiconductor layer can comprise p type, and the active layer 106 can be configured as a single heterostructure (SH), a double heterostructure (DH), a double-side double heterostructure (DDH), or a multi-quantum well (MQW) structure. The first electrode pad 110 is formed on a mesa of the lower semiconductor layer 104 by removing a portion of the upper semiconductor layer 108 and the active layer 106, and the second electrode pad 114 is formed on the upper semiconductor layer 108. The horizontal distance between the first electrode pad 110 and the second electrode pad 114 affects the output optical power and the forward voltage of the light-emitting device 100 which has a rectangle shape. Compared with the conventional light-emitting device, the first electrode pad 110 in the embodiment is located at a position closer to the second electrode pad 114, therefore a current for activating the light-emitting device can reach the first electrode pad 110 more easily, and the second section 110 a can also help to spread the current to the area between the first electrode pad 110 and the first side 111 a. In the present embodiment, the forward voltage of the light-emitting stack 111 can be between 3.05 V and 3.11V.

A second extension electrode comprising a first branch 114 a and a second branch 114 b can be extended from the second electrode pad 114. The first section 110 b can be positioned between the first branch 114 a and the second branch 114 b, and in the present embodiment, the first electrode pad 110 and the second section 110 a are also positioned between the first branch 114 a and the second branch 114 b. The ends of the first branch 114 a and the second branch 114 b can be closer to the first side 111 a than the end of the second section 110 a.

A portion of the upper surface 100 a that exposes the upper semiconductor layer 108 can be uneven, and a transparent conductive layer 112 can be conformably formed on the upper semiconductor layer 108. The transparent conductive layer 112 can be ITO, AZO, IZO, ZnO or other oxide material. A first current blocking layer 119 can be formed under the second electrode pad 114. The first current blocking layer 119 can be directly formed on a smoothing portion of the upper semiconductor layer 108, and the transparent conductive layer 112 can be formed between the second electrode pad 114 and the first current blocking layer 119. A second current blocking layer 121 can be formed under the first electrode pad 110, and in the first embodiment the second current blocking layer 121 is embedded in the first electrode pad 110 and has a side in contact with the lower semiconductor layer 104.

The light-emitting stack 111 can be formed on a substrate 102, and in the embodiment the substrate 102 is sapphire, and the light-emitting stack 111 comprises nitride-based material grown from the substrate 102 by epitaxial growth. However an adhesive layer (not shown) can be formed between the light-emitting stack 111 and the substrate 102 for attaching the light-emitting stack 111 on the substrate 102, and the light-emitting stack 111 can comprise AlGaInP-based material or nitride-based material, and the substrate 102 comprises insulating substrate such as sapphire or heat-dissipation substrate such as ceramic or metal.

Referring to FIGS. 2A and 2B, a light-emitting device in accordance with a second embodiment of the present application is disclosed, wherein FIG. 2B is a cross-sectional view of FIG. 2A along line CC′. A light-emitting device 200 comprises: a light-emitting stack 211 comprising a first side 211 a, a second side 211 b opposite to the first side 211 a, and an upper surface 200 a between the first side 211 a and the second side 211 b; a first electrode pad 210 formed on the upper surface 200 a; a second electrode pad 214 formed on the upper surface 200 a, and the first electrode pad 210 is closer to the first side 211 a than the second electrode pad 214; and a first extension electrode comprising a first section 210 a extended from the first electrode pad 210 and parallel to the first side 211 a, and a second section 210 b connected to the first section 210 a and perpendicular to the first side 211 a or the second side 211 b. The second section 210 b can be bended from the first section 210 a and has an end directing to the second side 211 b. The light-emitting stack 211 further comprises a third side 211 c and a fourth side 211 d opposite to the third side 211 c, and the first side 211 a, the second side 211 b, the third side 211 c and the fourth side 211 d form a rectangle, wherein the first side 211 a and second side 211 b are the shorter sides, and the third side 211 c and the fourth side 211 d are the longer sides. The first electrode pad 210 can be adjacent to the third side 211 c, and the second electrode pad 214 can be located near the corner between the second side 211 b and the fourth side 211 d. The light-emitting device 200 can further comprise a second extension electrode comprising a first branch 214 a and a second branch 214 b respectively extended from the second electrode pad 214, and the second section 210 b is between the first branch 214 a and the second branch 214 b. The first branch 214 a is a stripe parallel to the fourth side 211 d and is bended near the end thereof, and the end approximately directs towards the corner between the first side 211 a and the third side 211 c. The second branch 214 b can be initially an arc toward the second side 211 b and the third side 211 c, and then extended toward the first side 211 a with a stripe parallel to the third side 211 c.

A substrate 202 having an uneven upper surface 202 a is for supporting the light-emitting stack 211, and similar to the first embodiment, the light-emitting stack 211 can be formed on the substrate 202 by epitaxial growth or adhesive attaching.

Referring to FIG. 3, a light-emitting device in accordance with a third embodiment of the present application is disclosed. A light-emitting device 300 comprises: a light-emitting stack 311 comprising a first side 311 a, a second side 311 b opposite to the first side 311 a, and an upper surface 300 a between the first side 311 a and the second side 311 b; a first electrode pad 310 formed on the upper surface 300 a; a second electrode pad 314 formed on the upper surface 300 a, and the first electrode pad 310 is closer to the first side 311 a than the second electrode pad 314; and a first extension electrode comprising a first section 310 a extended from the first electrode pad 310 and parallel to the first side 311 a, and a second section 310 b connected to the first section 310 a and perpendicular to the first side 311 a or the second side 311 b. The difference between the third embodiment and the second embodiment is that the second section 310 b has two ends toward the first side 311 a and the second side 311 b, respectively, and a distance between the first electrode pad 310 and the first side 311 a is approximately the same with a distance between the first electrode pad 310 and the second side 311 b. A branch 314 a can be extended from the second electrode pad 314 and has a pattern surrounding the second section 310 b, and the branch 314 a has an opening 314 b for accommodating the first section 310 a.

The principle and the efficiency of the present application illustrated by the embodiments above are not the limitation of the application. Any person having ordinary skill in the art can modify or change the aforementioned embodiments. Therefore, the protection range of the rights in the application will be listed as the following claims. 

What is claimed is:
 1. A light-emitting device, comprising: a rectangular shape with a first side, a second side opposite to the first side, and a third side connecting the first side and the second side; a light-emitting stack, comprising a lower semiconductor layer, an upper semiconductor layer, and an active layer between the lower semiconductor layer and the upper semiconductor layer; a first electrode formed on the lower semiconductor layer, comprising a first electrode pad and a first extension electrode; a second electrode formed on the upper semiconductor layer, comprising a second electrode pad and a second extension electrode; and a first current blocking layer formed between the lower semiconductor layer and the first electrode pad, wherein the first current blocking layer comprises a top surface and side surfaces; wherein the first electrode pad covers the top surface and the side surfaces of the first current blocking layer and contacts the lower semiconductor layer.
 2. The light-emitting device according to claim 1, wherein the second extension electrode comprises a plurality of branches, and the first extension electrode is disposed between the plurality of branches.
 3. The light-emitting device according to claim 1, wherein the first extension electrode comprises a first section extends from the first electrode pad toward the second electrode pad and a second section extends from the first electrode pad toward a direction away from the second electrode pad.
 4. The light-emitting device according to claim 3, wherein the length of the first side is X, the length of the third side is Y, the length of the first section is a, and the length of the second section is b, and (a/b)=C(Y/X)−L, and C is a value between 1.5 and 2, and L is a value between 1 and 1.05.
 5. The light-emitting device of claim 4, wherein Y>X.
 6. The light-emitting device of claim 3, wherein the length of the first section is a, and the length of the second section is b; and wherein a>b.
 7. The light-emitting device of claim 3, wherein the second extension electrode comprises a first branch with a first end and a second branch with a second end; and wherein the second section extends without crossing an imaginary line linking the first end and the second end.
 8. The light-emitting device of claim 3, wherein the second electrode pad is adjacent to the second side, and the first section and the second section are parallel to the third side.
 9. The light-emitting device of claim 1, wherein the first extension electrode is parallel with the third side and the second extension electrode is an arc.
 10. The light-emitting device of claim 1, wherein: the first electrode pad is formed adjacent to the third side; the second electrode pad is formed adjacent to the second side; and the first extension electrode extends from the first electrode pad in a direction away from the third side and bended toward the second side.
 11. The light-emitting device of claim 10, wherein: the second extension electrode comprises a first branch and a second branch respectively extended from the second electrode pad; a distance between the first electrode pad and the third side is smaller than a distance between the second electrode pad and the third side; and an end portion of the first branch comprises a first arc bending to the third side and a minimum distance between the first branch and the first side is smaller than a minimum distance between the second branch and the first side.
 12. The light-emitting device of claim 11, wherein the second branch comprises a second arc connecting the second electrode pad and a stripe connecting to the second arc, and the stripe is parallel with the third side.
 13. The light-emitting device according to claim 1, further comprising a transparent conductive layer formed on the upper semiconductor layer.
 14. The light-emitting device according to claim 1, further comprising a second current blocking layer under the second electrode pad.
 15. The light-emitting device according to claim 1, wherein the first electrode pad has a width larger than that of the first current blocking layer.
 16. The light-emitting device according to claim 1, wherein the first current blocking layer is embedded in the first electrode pad. 